A cosmetic brush used for applying a liquid cosmetic material such as mascara generally includes, as described in Patent Document 1, a core wire part and a bristle group (a brush bristle group, a needle bristle group) radially attached to the core wire part around an axis of the core wire part continuously in a helical state in the axial direction of the core wire part.
In this brush, the bristle group constitutes a substantially columnar brush part, and the bristle group can be immersed in a liquid cosmetic material to cause the liquid cosmetic material to adhere to bristles in the bristle group such that the liquid cosmetic material is retained between the adjacent bristles. Therefore, by putting a side surface of the bristle group to an object of application such as the eyelashes, the liquid cosmetic material retained in the bristle group can be applied to the object of application.